Repeat expansions are a special class of microsatellite and minisatellite variants involving short tandem repeat (STR) polymorphisms. Repeat expansions are also known as dynamic mutations due to their instability when short tandem repeats expand beyond certain sizes. Genetic disorders caused by unstable repeat expansions include, among others, fragile X syndrome (FXS), Huntington's disease, and amyotrophic lateral sclerosis (ALS).
Identifying repeat expansions is important in the diagnosis and treatment of certain genetic disorders. However, it is difficult to determine repeat sequences using short reads that do not fully traverse the repeat sequence. Therefore, it is desirable to develop methods using short reads to identify medically relevant repeat expansions.